The present invention relates to a mechanized unit for digging a trench in the ground and laying elongate objects or similar in said trench.
Although not exclusively the mechanized unit of the invention is more particularly intended for laying electric or telephone cables or flexible pipes or ducts in the ground. Mechanized units are already known for carrying out these different operations. Such a mechanized unit includes more particularly a motor driven vehicle, generally a tractor or a public works vehicle, on which are mounted, for example in front of the vehicle, a reserve containing said elongate objects and, at the rear of the vehicle, a digging wheel for digging the trench. In general, a guide device for laying the elongate objects in the bottom of the trench is connected to the vehicle and causes the objects to assume a given curvature so that they are suitably laid in the bottom of the trench.
Thus, during movement of the motor driven vehicle, the digging wheel, driven by a motor, digs a trench while discharging the earth on each side thereof and, simultaneously with its formation said objects pass through the guide device and are laid in the bottom of the trench. This type of mechanized unit has however drawbacks. In fact, the bottom of the trench thus formed is very often formed of an amalgam of earth and rocks which are more or less sharp and cutting. Thus, the objects or similar risk being damaged in contact with the rocks and stones. Beginnings of cracks and slits then appear in the protective coating of said objects and may subsequently cause stripping of said objects or breakage thereof. This risk of damage is all the greater since the amalgam of earth and rocks discharged on each side of the trench during formation thereof is brought back therein. In fact, under the action of the weight of this amalgam, the objects are pressed against the bottom of the trench and so against the sharp edges of the rocks. In addition, sharp rocks, during filling of the trench fall directly on the objects thus causing cuts therein.
Furthermore, another drawback of the presently known mechanized units resides in the fact that the amalgam of earth and rocks removed from the trench is brought back therein either by means of an other vehicle adapted for this type of filling operation or manually, workmen equipped with shovels filling the trenches. Whatever the solution used, it causes an additional cost.
The aim of the present invention is to overcome these drawbacks and relates to a mechanized unit for digging a trench and laying elongate objects in said trench which avoids the risks of damage to said elongate objects and which may also fill the trench thus formed, once said elongate objects have been laid.